Ratio question

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ashforgmat: Senior | Next Rank: 100 Posts; Posts: 71; Joined: Sun Feb 21, 2010 9:16 pm; Thanked: 3 times; GMAT Score:750

Ratio question

by ashforgmat » Sun May 16, 2010 9:29 pm

198) All the clients that company x had at the beginning of the year remained with the company for the whole year. If Company x acquired new clients during the year, what was the ratio of number of clients that Company X had at the end to no. of clients that Company X had at the beginning of the year? A
a. Ratio of no. of clients that Company X had at beginning of last year to no. of new clients that it acquired during the year was 12 to 1.
b. Company X had 144 clients at beginning of last year

Please can someone provide explanation...

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Source: Beat The GMAT — Data Sufficiency | Sun May 16, 2010 9:29 pm

ballubalraj: Senior | Next Rank: 100 Posts; Posts: 66; Joined: Tue Dec 15, 2009 3:07 am; Location: Bangalore; Thanked: 9 times; GMAT Score:730

by ballubalraj » Mon May 17, 2010 12:26 am

Let Old Clients = O, New Clients = N

Statement 1: Gives the ratio of Old clients to new clients (O/N) = 12/1. No other information about any of the numbers. Hence, the the ratio O+N/O can not be determined. Insufficient.

Statement 2: O = 144; no information on new clients. Hence, the the ratio O+N/O can not be determined. Insufficient.

Both stmt 1 and stmt2 together:

O/N = 12/1, as O = 144, N = 144/12 = 12, which leads to O+N/N = 156/144; sufficient.

Answer C.

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mj78ind: Master | Next Rank: 500 Posts; Posts: 265; Joined: Mon Dec 28, 2009 9:45 pm; Thanked: 26 times; Followed by:2 members; GMAT Score:760

by mj78ind » Mon May 17, 2010 12:45 am

Per A, let o = old, n = new. Then o/n = 12/1, hence o/(o+n) = 12/13. { n/o = 1/12 adding, 1 to each side gives, (n+o)/o = 13/12, taking the reciprocal gives us 12/13)

Hence, A